Hundreds, possibly thousands, of drivers are injured annually because they accidentally drive off of a roadway. Some drives are actually killed as their vehicle impacts objects, such as trees or other immobile objects, at high speeds.
Often, the vehicle is driven off of the roadway due to simple inattentiveness by the driver, or because the driver has fallen asleep at the wheel.
While the art does contain sleep alarms such as devices that are worn by the driver and which will emit an audible alarm signal should the driver's head droop, such devices are dependant on driver movement Should the driver be otherwise alert, but simply not paying attention to the road itself, such devices may not be effective. Thus, many driver alarms are inferential in nature in that they infer a potential danger due to the existence of another condition, such as a driver's head nodding. This is not always the most effective way of protecting the driver or the passengers of a land motor vehicle.
Still another situation that exists in which the driver may accidentally drive off of the roadway while being quite alert, is the situation in which the roadway is not fully visible, such as at night, or under snow conditions. The driver may be drifting towards the roadway side and yet not know it, or be trying to turn into a cross street before or after the intersection of that cross street and the roadway. In situations such as this, the driver may still drive off of the roadway, yet the abovedescribed devices will be of little use in warning him of the impending mistake.
Still further, the alarm devices, such as just described, do not differentiate to the driver what sort occurrence is being signaled. Thus, the driver is not given sufficient information to make a proper correction by such devices. For example, if the driver is simply drifting toward an incorrect driving path, that driver should be warned in a manner that will permit a gentle correction; however, if the vehicle is swerving dangerous)y into a dangerous path, the driver should be warned in a manner that will cause a rapid and strong correction. On the other hand, it is not desirable to cause the driver to swerve when only a gentle correction is necessary. An improper driving correction may be ineffective at best if the driver attempts to gently correct when a sharp swerve is required, and dangerous at worst if the driver swerves into an oncoming lane of traffic while under the impression a swerve maneuver is required when only a gentle correction maneuver is actually required. Since present devices do not make such distinctions in the alarm condition, they are prone to delivering a warning containing insufficient information to take the most effective and safest corrective maneuvers.
Therefore, there is a need for an alarm system for use in a motor land vehicle to warn the driver that the vehicle is either too close to the edge of the roadway or is approaching that roadway edge at a dangerous velocity, and which can be used even if the roadway edge is not visible to the driver, and that is capable of providing condition-specific information to the driver to enable that driver to take the corrective action that is safest and most desirable for the particular condition that exists.